Mayo researchers link vaping illness to toxic inhalation

New research from Mayo Clinic suggests that the nation's outbreak of vaping-related lung injuries is due to people inhaling toxic substances — akin to workers who breathe fumes from chemical spills, or World War I soldiers exposed to mustard gas.

The finding by Mayo's consulting pathology lab in Arizona is based on a first-ever examination of 17 biopsies of patients with vaping-associated lung injuries. While the role of chemical inhalation might sound obvious, the finding is important because it contradicts a popular theory that these cases were caused by oil or lipid contamination in the lungs.

"It seems to be some kind of direct chemical injury, similar to what one might see with exposures to toxic chemical fumes, poisonous gases and toxic agents," said Dr. Brandon Larsen, a surgical pathologist at Mayo Clinic Arizona, who reported the findings Wednesday in the New England Journal of Medicine.

While the 17 biopsies found macrophages — white blood cells that are dispatched to eat harmful contaminants — they found no large deposits of oil or lipids (a kind of fatty organic compound) in the lungs.

The national outbreak of vaping-related illnesses now includes 805 severe lung injuries and 12 deaths this year, according to the Centers for Disease Control and Prevention (CDC). In Minnesota, state health officials have reported one death and 59 confirmed or probable injuries, with another 32 cases under review. Many of the cases involved otherwise healthy teens and young adults who required hospital intensive care and respirators to maintain breathing.

Mayo doctors have contacted the CDC about whether their pathology findings will lead to an updated diagnostic definition of the vaping-associated lung injuries. Larsen stressed that the finding does not absolve any particular chemical or culprit, including the oils, vitamin E or other substances that are used to thicken vaping juice.

"Everything is still on the table," Larsen said. "I am skeptical that vitamin E is the sole culprit, if even the culprit at all. Maybe it's important, but I think we can't stop looking."

Mayo's findings also don't pin the blame on vaping illicit marijuana or its psychoactive component, THC, instead of legal nicotine e-cigarette products. Twelve of the cases in the report involved vapers who inhaled marijuana products. Two cases in the Mayo review involved deaths.

Minnesota health investigators have interviewed 29 of the state's lung-injured patients, and 27 have acknowledged vaping THC products. Two said they only vaped nicotine, but one was found to be in possession of a THC e-cigarette cartridge.

Despite the evidence implicating THC, state health officials aren't absolving legal nicotine products. Citing new survey data about rising e-cigarette use by Minnesota high school students, Gov. Tim Walz on Wednesday proposed heightened public education on the dangers of vaping in general, and he said his administration will consider legislation to raise the smoking age or ban the sale of flavored tobacco.

The 2019 edition of a student survey conducted by the state Health Department found a sharp increase in use of e-cigarettes, with 26.4% of 11th-graders saying they had vaped at least once in the prior month, up from 17.1% in 2016.

Mayo operates a pathology lab at its Scottsdale campus that has long consulted with doctors and provided second opinions about biopsy and test results. Larsen said it has actually received reports of vaping-associated lung injuries over the past two years, even though the current outbreak was only identified earlier this year. The existence of earlier cases casts doubt on the idea that the illnesses resulted from a new ingredient or type of vaping product or delivery device.

"It's probably a more complex problem," Larsen said. "It goes beyond one bad batch."

The theory that oils or lipids caused these injuries has persisted because biopsies aren't commonly ordered for these lung injury cases, Larsen said. It also takes a review of multiple biopsies to detect a pattern.

Pneumonia or lung injury caused by lipid oil contamination is somewhat rare — with some cases being reported among entertainers who perform fire-breathing and accidentally swallow kerosene. It has also been reported among seniors who use oily substances to clear their sinuses, Larsen said.

"Like they'll put a bunch of Vaseline in their noses and then they'll lie down to sleep," he said, "and the Vaseline will gurgle into their lungs."

Mayo is continuing to gather biopsies from lung-injury cases. Larsen said he hopes these findings will guide public policy that governs or restricts e-cigarettes, and the ongoing federal and state searches for the cause of the outbreak.

"What should we be looking for? What should we be focusing our efforts on?" he said. "This data says we should be looking for toxic chemical constituents in these materials."